In the 2003 case United States v. Manuel Flores-Montano, the U.S Supreme Court unanimously ruled that customs officials do not need reasonable suspicion to disassemble a vehicle's gas tank at an international border in order to search for contraband. The decision came after Manuel Flores-Montano was arrested when 37 kilograms of marijuana were found in his car's fuel tank by customs officers at the Otay Mesa Port of Entry near San Diego, California. His defense argued that dismantling parts of a vehicle constitutes an intrusive search and should require some level of suspicion under Fourth Amendment protections against unreasonable searches and seizures. However, Justice O'Connor wrote for the court stating that "the government’s interest in preventing entry of unwanted persons and effects is at its zenith" at international borders.

In the case of United States v. Manuel Flores-Montano, there was no formal dissenting opinion recorded by any of the justices. The unanimous decision upheld that customs officials do not need reasonable suspicion to disassemble and search a vehicle's gas tank at international borders or their functional equivalents. This ruling emphasized the long-standing right of sovereign nations to protect their territorial integrity through routine searches and seizures at border crossings, without violating Fourth Amendment protections against unreasonable searches and seizures.